Block-signal system.



L. A. HAWKINS.

BLOCK SIGNAL SYSTEM.

APPLIOATION FILED AUG. 7. 1909.

1,094,441 Patented Ap1'128, 1914.

3 SHEETS*SHEET 1.

ki/ fi@ @MJ/QM l COLUMBIA PLANOGRAPH C0., wASHlNGroN. D. c4

L. A. HAWKINS.

BLOCK SIGNAL SYSTEM.

vAPPLICATION FILED AUGJI, 1909.

1,094,441 Patented Apr. 28, 1914.

3 SHEETS-SHEET 2.

COLUMBIA PLANOGRAPH c0..w^sHlNcToN. D. c.

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L. A. HAWKINS.

BLOCK SIGNAL SYSTEM.

APPLICATION FILED AUG. 7, 1909.

CDLUMBM PLANOGRAPH co..WAsH|NGTON. D. c.

Patented Apr. 2s, 1914.

3 SHEETS-SHEET 3.

NETE@ STATES PATENT OFFCE.

LAURENCE A. HAWKINS, OF SCHENECTADY, NEW YORK, ASSIGNOR, BY MESNE AS- SIGNMENTS, TO THE UNION SWITCH AND SIGNAL COMPANY, .A CORPGRATION F PENNSYLVANIA.

stock-SIGNAL SYSTEM.

i ,cansan Continuation of application Serial No. 495,100, led May 10, 1909.

Specification of Letters Patent.

Serial No. 511,663.

To alt lwhom t may concern Be it known that l, LAURENCE A. Hawkins, a citizen of the United States, residing at Schenectady, county of Schenectady, State of New York, have invent-ed certain new and useful improvements in Block-Signal .Systcms, of which the following is a specification.

This case is in part a continuation of my prior application, Serial. No. L@5.100, tiled May l0, 1909.

Bly invention relates to alternating current block signal systems employing signals arranged to indicate danger, caution and clear, either' by a three position arm or by home and distant signals, and more particularly to systems in which the operation of a signal from caution to clear is produced by means of a switch included in the track circuit of the block guarded by the signal and actuated by the movement from danger to caution of the signal of the block in advance. Such a system is shown in Patent No. '-ejQQO, issued to F. B, Corey, February 26, 1907.

The object of my invention is to improve the efliciency of such a system, and to remove certain disadvantages inherent in all prior systems of this character.

In the system shown in the above-mentioned patent two track relays of different types are employed for each block; one relay has a single windinO supplied from the track circuit and responds to current of any phase, while the other has two cooperating wind ings, one supplied from the track circuit and the other' supplied independently of the track circuit with current of a certain phase, so that the current in the track circuit must have a certain phase relation to the current in the second winding of the relay in order that the relay may operate. A relay of the latter type is more e'liicient than a relay with a single winding for the reason that the greater part of the power required can vbe supplied directly and efiiciently from the transmission line, while in the relay of the single winding type all the power must be supplied through the track circuitI with considerable loss. Furthermore, it is advantageous from the maintenance standpoint to have all the track relays of the same construction. By my invention all the relays may be of the e'liicient twowinding type. l

accomplish this result by supplying those windings of the two relays which are not connected to the track circuits with currents differing in character, preferablyof diiferent phase. lfilhen one relay only is to be energized, that is, when the signal in advance is at danger, a current is supplied to the track circuit of such a character as tc actuate one track relay only. When the signal in advance has moved to caution, the supply connections for the track circuit are so changed that the current is then of a character adapted to operate bot-h relays and preferably of a phase half way between the phases which would give maximum torque in the two relays respectively. Since the phase of the track current is not reversed but only shifted through a certain angle (preferably approximately 90o) it is possible to arrange the switch controlling the phase of the track current so as to shift the phase gradually without interrupting the flow of current to the track circuit. By means of such an arrangement a constant torque is maintained on the relay already energized, so that there is no danger of this relay opening its contacts and tripping the signal while the switch is being actuated.

A very important advantage, resulting from the fact that the phase of the track current is not reversed, and that the relays are of the two winding type is the possibility of avoiding by reversing the connections of the transformers for adjacent track circuits, all danger of false clear signals, due to leakage from one track circuit to another by the breaking down of insulated joints, or otherwise. Since the relays can be energized only by current in a certain direction in the track windings, the leakage current from one section to another will because of the reversal, be in such a direction as to create a reverse torque in the relays. This is of particular importance in alternating current systems, since the track voltages employed are ordinarily higher than are used in direct current systems, and the insulated oints are therefore more likely to break down.

My invention will best be understood by reference to the accompanying drawings, in whichs Figure 1 shows diagrammatically one embodiment of a block signal system arranged in accordance with my invention; Figs. 2 to 7 inclusive are explanatory diagrams, Fig. 8 shows a modiiication of the system; Fig. 9 shows a modii'ication adapted for use with cut sections, and Figs. l0 to 14e are explanatory diagrams.

ln Fig. l, A0 to A2 represent the track rails divided into four blocks which l have indicated as separated from each other by insulated joints, as in ordinary steam road practice. It will be understood, however, that my invention is applicable to electric roads having any suitable arrangement of track circuits. B represents a two-phase generator which supplies the current for the signal circuits through the transmission lines I), b', b2. l have indicated a two-phase threewire transmission, the wire 7) serving as a common return for both phases. C to C5 represent transformers having their primaries connected to the different phases of the transmission circuit and their secondaries adapted to he connected through impedances E to Fi2 to the track. The way in which theseI transformers are connected will be described later. The impedances E to E2 are provided for the purpose of preventing the transformers from being short-circuited by a train. D to D5 represent track relays which are indicated diagrammatically as of the well-known induction type, each comprising a short-circuited secondary member Z actuating the relay contacts, a winding d connected to the track rails, and a second cooperating winding (Z2 supplied with alternating current independently of the track circuits. These second windings ot the relays and also the mechanisms of the home and distant signals F, F', F2, G, G and G2, may be supplied -trom the secondaries of the same transformers that supply the track circuits. There are a pair of relays for each track circuit, and the windings Z2 of each pair of relays are connected to the secondaries of diiierent transformers, so that the currents in the windings of the two relays are displaced from each other approximately 90O in phase. j' represents a switch actuated by the home signal, as indicated diagrammatically by dotted lines, and controlling the operating mechanism of the distant signal. f represents a movable contact or sector actuated by the home signal and provided with stationary contact nngers f2, f2 and f4. It is these fingers that control the phase of the currents supplied to the track circuit for the block next in the rear.

The operation is as follows: lith a train in block A2, as represented in Fig. l, the track windings of both relays D4 and D5 are short circuited, so that the relay contacts are open and signals F2 and G2 both stand at stop position. ln this position ot the signal F2 the movable contact f connects contact fingers f2 and f3. Through these ting-ers the secondary of transformer C* is connected to the track rails through one oit' the impedances E2. The relative phase of the currents in the windings of the relays D2 and D are then as shown by the diagrams of Figs. 2 and 3 respectively, in the diagram ot' Fig. 2 0 1." represents the phase of the secondary voltage of both transt'ormers C2 and C4, the iirst of which is connect-cd to the winding (Z2 of relay D2 and the second to the track rails. lf the impedance E2 is .non-inductive, the track ci cuit with this impedance in series with it has a i'airly high power factor, so that the current supplied to the track circuit A from transformer C* may be represented by 0 lagging behind the secondary voltage ot transformer C* by the angle /U 0 The winding (Z2 of relay D2 has a comparatively low power factor, so that the current in this relay winding may be represented o 2". rlhe current in the relay winding d is the current in the rail circuit, that is, 0 There is, consequently.v a phase displacement between the two windings of the relay D2 represented by the angle 'i 0 t", and it the circuits are suitably arranged this angle may be made equal to about 45. It', as stated, the impedance FP is non-inductive, approximately this angle will be obtained with the precise connections shown. It' the impedance E2 is made inductive, so as to economize power, and the track current lags by a large angle behind the voltage, the proper phase angle between the currents in relay windings d and (Z2 may he obtained by adjusting the phase of the 1foltage impressed on the winding d2 of relay D2, as will be obvious to those skilled in the art. Since two phase voltages from the secondaries of transformers C2 and C2 are available at relays D2 and l)3 the phases ot' the voltages impressed on the windings ct' these two relays may readily he made anything desired. n relay D3 the conditions are as indicated in Fig. 3 where the voltage and current impressed upon the winding Z2 of the relay are as indicated by 0 rr2 and o i2. respectively, the current in the winding (Il being the same as in the corresponding winding of relay D2 and represented by 0 1'. Comparing Figs. 2 and 3 it will be seen that. the current in the winding CZ, that is, 0 f2', in each relay, is displaced about 450 from thc current in the other winding, but in relay D2 it leads the other current by 45, while in relay D2 it lags behind the other current by 450. It the relays` are so connected that a torque tending to close the relay contacts is produced when the current in the track winding leads the current in the other winding, then relay D2 will have such a torque while relay D2 will have a reverse torque. Under these conditions relay D2 will close its contacts, clearing home signal F', as

izo

shown, While relay D3 will have a reverse torque holding its contacts in open position so that distant signal G will stand at stop, as shown. Jhen the block i 2 is cleared relay D4 will close its contacts in the same manner as relay D2 has closed its contacts, and the signal F2 will begin to clear. Vhen the contact f" reaches an intermediate position it engages all three fingers f2, 7' and f* connecting transformers C4 and C5 in parallel across the rails ot track circuit A. iWhile this connection lasts, some current fiows through the two transformer secondaries in series, but it is limited in amount, since it must flow through both impedances E2 in series. So far as the etiect on the track circuit is concerned, the voltage and current are in phase hali way between what they would be with the transformers Ct and C5 separately connected to the track. In other words, the current in the track circuit is advanced 450 in phase. This is shown in Figs. l and 5, in which the track current 0 t' is shown advanced 452 with respect to Figs. 2 and 3. Conditions in relay D2, shown in Fig. 4e, have not been changed, except to increase somewhat the relay torque, since the phase displacementof the currents in the two windings is now 902 instead ot only 452. In relay D2, as shown in Fig. 5, the track current 0 i is in phase with the current o 'i2 in the other relay winding. rEhe relay, therefore, has no torque, but its contacts are held open by gravity. As the nal F2 completes its movement to clear po sition, the contact leaves contact linger f2, opening the connections from the transformer C2c to the track and leaving transformer C5 alone connected to the track rails. The conditions are then as represented at contact f of signal F and at relays D and D, and the relative phases of the currents in the relay windings are as indicated in Figs. 5 and 7. The track current o now leads the current o c" in the winding (Z2 of relay D by 1350, so that the torque in relay D is the same as under the conditions first der scribed for relay 2 and shown in since the sine of 1350 is the same as the sine of i-50. Tn relay D there is a phase displacement of 452 between the track cur` rent 0 z' and the current in winding (Z2, that is, o 2, as shown in Fig. 7, but the track current leads the current in the other winding of the relay instead of lagging behind it, as in relay D3 of Fig. 3, so that the relay D has a torque causing it to clear the distant signal G. It will be seen that when the phase of the current in the track circuit is the transformers of adjacent track circuits are relatively reversed in adjacent blocks. This has not been mentioned in the foregoing discussion since the connections from the track windings off the relays are also relatively reversed, so that as far as the preceding discussion is concerned the relative phases ot' the currents are not atfected by this double reversal. Reversal becomes ot' importance, however, upon leakage of current` from one track circuit to another, either by breaking down of insulated joints, or otherwise, .for it will be seen that any current leaking to relays D2 and D3 trom either transtormer C2 or C3 will be of a phase opposite to 0 'i in Fig. 2 or Fig. 6, depending upon the position of the signal F and contact f at the time. In either case this current will be such as to produce a reverse torque in relay D2, and, it signal F is clear, in relay D3 also, so that the signal F', if not at stop position, will be thrown to stop position and signal G, if not at stop position, will be thrown to stop position and retained there by the opening of contact f. Thus, regardless ot the phase of the current which is being impressed upon the track circuit no false clear indiations cau be obtained by leakage from one track circuit to the other.

While in Fig. 1 it is the track windings of the relays that are shown relatively reversed in adjacent blocks, it is obviously immaterial which ofthe two windings are so reversed.

Fig. 8 shows a modification of the system, in which the operation is precisely the same as betere described, the only differences between Figs. 1 and S being` in details of arrangement. ln the first place, one-arm three-position signals are shown for the purpose of giving the three indications, instead of the two-arm two-position signals of Fig. 1. This difference is wholly immaterial as regards my invent-ion. ln the second place, instead ot a two-phase transmission system, av three-phase transmission system is used, supplied by a three-phase generator B, as shown, and the two-phase relation. of voltages obtained on the secondary side ot the transformers C' to C5 by what is known as the three-ilihasc, two-phase connection or T connection oi the primaries. This also innnaterial with respect to my invention. The third difference between Figs. 1 and 8 is the addition of small transformers, c to r2 inserted between the secondaries of the main transt'criners and the track. The advant Y ot' employing this additional small trans o-rmer is that the same main transformers C to C5 may be employed for a plurality of tracks, without introducing any electrical connection between the different tracks, a separate small track transformer, being employed -for each track circuit. The

impedances E to E2 are placed in series with the secondaries of the main transformers and. therefore7 on the primary side of the small track transformers. The impedances thus placed prevent short-circuiting of the main transformers just as if placed on the secondary side of the small track transformers and at the same time serve the same purpose as in Fig. 1 of preventing short circuiting of the main transformers by the contact 7" when engaging both fingers f2 f4.

Fig. 9 shows the systei modified for use with subdivided blocks or cut sections. The track circuits or sections A and A compose one block. A2 and A2 another, etc. The arrangement at the signals is the same as shown in Fig. 8. except for minor changes in the circuit connections which have no effect on the operation. For t-he sections and A2 ther are no signal mechanisms for controlling the phase. so this is accomplished by means of the track relays of sections er and Af. respectively. The windings of these relays are connected the same as the windings of the relays at the signals. and their contacts are arranged to produce the same circuit changes as the contacts on the signal mechanism. This is shown diagrammatically in the diagrams of Figs. 10 to 1/-1 which show the conditions in the iive pairs of relays of Fig. 9. Fig. l() corresponds to relays DS and D9 in which the voltage and current in winding (Z2 of relay D8 are indicated by o c and 0 i. respectively, and the voltage and current in the winding` (Z2 of relay Dn by 0 r2. o 2'2. respectively. The track windings of the track relays are short-cir cuited. so that there is no current flowing through them and neither relay has any torque. Consequently, the transformer CS is connected to the primary of track transformer cAL of track circuit Ai". so that the current in the track circuit is as represented by o ef .iu Fig. 11. giving a torque in relay D6 causing it to close its contacts and giving a reverse torque in relay D7. it will be noted that as long as a train was in section A3 both relays DG and DT were deeiiergized and the opening of the contacts of relay DG disconnected the primary of track transformer c3 from the secondaries of the main transformers C and CT. so that relays DH1 and D5 were then dcnergized and the signal F stood at stop position. liVith the energizing of relay D, however, transformer C6 is connected to the primary of transformer c3, so that the current in track circuit A2 is of the same phase as that in track circuit A3 and the conditions of relays D and D5 are as indicated in Fig. l2; that is. the same as the conditions of relays D6 and DT in Fig. 1l. Signal F has, therefore, moved to caution position. l first connecting the secondary of transi former C5 in parallel with the secondary of i transformer Ct and then opening the circuit of the latter transformer so as to leave the primary of track transformer c2 connected to the secondary of the main transformer C5 only. The phase of the track current in section A is, therefore, as shown by o a' in 13, so that both relays D2 and D3 arc energized. as indicated in Fig. 13. The energization of relay D'2 has connected the primary of track transformer c to the secondary of transformer C2 instead of transformer C2, so that the phase of the current in the section A is the same as that in section and the conditions in relays D and D', shown by Fig. '14, are the same as in relays D2 and D2. shown by Fig. 1S. The contacts of relay D3 are made flexible. as diagrammatically indicated. so that the front contacts are closed before the back contacts are` opened. thus shifting the phase of the track current in the adjacent track circuit gradually without. interrupting the flow of the track current. In other words. the contacts of this relay produce the same circuit changes in the same sequence as the movable contact j. on the signal shaft. The san e arrangement may obviously be repeated to operate blocks with as many cut sections as desired.

lt. will be noted in Figs. S and 9 that the circuit changes produced by the movement of contact f occur while the signal is moving from danger to caution. which movement corresponds to the clearing of the home signal in Fig. 1. TWhile the signal in Figs. 8 and 9 moves from caution to clear no change in circuit connections is produced. in the drawings the signals have been indicated diagrammatically in the usual conventional manner, the signal mechanisms themselves being omitted in order to prevent complicating the drawings. lt will be understood in Figs. S and 9 that the conductor leading to the lower side of the blade is the common conductor for both the caution and clear positions, the circuit controlling the caution position being completed through the contacts of relay D. D2, etc., and the circuit controlling the clear position extending through the contacts of relay D D3. etc., in series with contacts of relays D, D2 etc. lf the signal mechanisms are single phase, the loads on the different phases of the transmission system may be balanced as indicated in Fig. 8. by connecting alternate signal mechanisms of the same track to different phases. or, in the case of roads having a plurality of tracks. the signal mechanisms for one track may all he connected to the same phase. as indicated in Figs. 1 and 9.

l. do not desire to limit myself to the particular connections and arrangements nor to the particular difference in character of current or to the method of obtaining it l shown and described but aim in the appended claims to cover all modifications which are within the scope of my invention.

lilhat l claim as new and desire to secure by Letters Patent of the United States, is

l. ln a block signal system, signals for the bloc adapted to indicate danger, caution, and clear, track circuits for the blocks, sources of alternating current for the track circuits, a pair of track relays for each block controlling the caution and clear indications according` as one or both relays are energized, said relays having windings supplied with current troni the track circuit and cooperating windings supplied with alternating current independently of the track circuit, the currents supplied to said latter windings diiiiering in character in the two relays ot' each pair, and means controlled by thc presence or absence of a train in one block for controlling the character of the current supplied to the block in the rear ot' said means so as to actuate one only, or both, ot the pair oi relays for said block in the rear.

2. ln a block signal system, signals for the blocks adapted to indicate danger, caution, and clear, track circuits for the blocks, irces of alternating current for the track circuits, a pair ot track relays for each block controlling the caution and clear indications according as one or both relays are energized, said relays haring windings supplied with current from the track circuits and coperat- .ing` windings supplied with alternating current independently ot the track circuits, the currents supplied to said latter windings ditt'ering in character in the two relays of each pair, and connections including a switch actuated by the movement of a signal from danger to caution for supplying` in one position ot said switch to the rails of the block in the rear current ot' a character adapted to actuate one track relay only of said block and in another position of said switch tor supplying to the said rails current ot a character adapted to actuate both relays ot said blocks.

.2%. ln a block sfgual system, signals for tac blocks adapted to indicate danger, caution.. and clear, track circuits for the blocks, sources ot zltcrnatiug currentfor the track circuits, a pair ot track relays for each block controlling the ,caution and clear indications accordingl as one or bot-h relays are energized. said relays haring windings supplied wit-h current from the track circuit and v operating windings supplied with alternating current independently of the track circuit, the currents supplied to said latter windings differing in character in the two relays ot each pair, the pairs of relays ot adjacent blocks being reversely connected, and means controlled by the presence or absence ot a train in one block for controlling the character of the current supplied to the block in the rear ot said means so as to actuate one only, or both, of the pair of relays for said block in the rear.

et, ln a block signal system, signals for the blocks adapted to indicate danger, caution, and clear, track circuits for the blocks, sources of alternating` current for track circuits, a pair of track relays for each block controlling the caution and clear indications according as one or bot-h relays are energized, said relays having windings supplied with current from the track circuit and cooperating windings supplied with alternating current independently of the track circuit, the currents supplied to said latter windings differing in character in the two relays of each pair, and connections including a switch actuated by the movement of a signal from danger to caution for supplying in one position of said switch to the rails of the block in the rear current of a character adapted to actuate one track relay only of said block and in another position for supplying ot said switch to the said rails current of a character adapted to actuate both relays of' said blocks, thesources and relays of adjacent blocks being reversely connected so that current from the source tor one block produces a reverse torque in the adjacent relays upon the breaking down ot the insulated joints between them.

in a block signal system, signals for the blocks adapted to indicate danger, caution, and clear, track circuits for the blocks, sources ot' alternating current for the track circuits, a pair ot' track relays for each block controlling the caution and clear indications according as one oi both relays are energized, each ot said relays having a winding supplied with current from the track circuit and a cooperating winding supplied 'ith alternating current independently of the track circuit, one or" said relays being responsive to a current in the track rails of a character to which the other does not respond, and connections including a switch actuated by the movement of a signal from danger to caution for supplying in different positions ot said switch currents ot different character to the track rails of the block in the rear, the sources and relays of adjacent blocks being` reversely connected so that current from the source tor one block produces a reverse torque in the adjacent relays upon the breaking down of the insulated joints between them.

(i. ln a block signal system, blocks having a plurality of cut sections, a track circuit for each cut section, signals for the blocks adapted to indicate danger, caution, and clear, means i'or supplying alternating currents diti'ering in character for the track circuits,

a pair of track r'elays for each track circuit l or section, haring windings supplied withf current from the track circuit and coperating windings supplied with alternating current independently of the track circuit, the currents supplied to said latter' windings dittering' in character in the two relays of each pair, the two relays of the first track circuit or section of each block controlling the caution and clear indications of the signal for such block according as one or both re lays are energized and the two relays of the track circuit or section next in advance controlling the character of the current supplied to the first track circuit or section.

T. ln a block signal system, blocks having a plurality of cut sections, a track circuit for each cut section, signals for the blocksl adapted to indicate danger, caution, and clear, means for suiiplying alternating currents diiiering in character for the track circuit, a pair of track relays for each track circuit or section, haring windings supplied with current from the track circuit and cooperating' windings supplied with alternating currentindependently of the track circuit, the currents supplied to said latter windings differing in character in the two relays of each pair, the two relays of the first track circuit or section oi' a block controlling the caution and clear indications of the signal for such block according as one or both relays are energized, means controlled by the presence or absence of a train in one block for controlling the character of the current supplied to the adjacent track circuit or section oi the block next in the rear of said means, and contacts controlled by the two relays of said last named track circuit or section for controlling the character of the current supplied to the track circuit or section next preceding'.

S. In a block signal system, signals for the blocks adapted to indicate danger, caution, and clear, track circuits for the blocks, sources of alternating' current for the track circuits, a pair of track relays for each block controlling' the caution and clear indications according' as one or both relays are energized` each of said relays having' a winding supplied with current from the track circuit and a` second cooperating winding supplied with alternating current independently of the track circuit, the currents supplied to said second windings differing in phase in the two relays ot' each pair, and means controlled by the presence or absence of a train in one block for controlling the phase of the current supplied to the block in the rear of said means so as to actuate one only, or both, of the pair of relays for said block in the rear.

9. in a block signal system, signals for the blocks adapted to indicate danger, caution,

and clear, track circuits for the blocks, sources of alternating current for the track circuits, a pair of track relays for each block controlling the caution and clear indications according as one or both relays are energized, cach of said relays having a winding supplied with currcnt from the track circuit and a second coperating winding supplied with alternating current independently ot the track circuit, the currents supplied to said. second windings differing in phase in the two relays oi' each pair, and means controlled by the movement of a signal from danger to caution for gradually shifting the phase of the current supplied to the rails of the block in the rear without interrupting the current flow.

l0. ln a block signal system, signals for the blocks adapted to indicate danger, caution and clear.l track circuits for the blocks, sources of alternating current for the track circuits, a pair ot' track relays for each block controlling the caution and clear indications according as one or both relays are energized, each ot' said relays having a winding supplied with current from the track circuit and a second coperating winding supplied with alternating current independently ot the track circuit, the currents supplied to said second windings differing in phase in the two relays of each pair, and connections including a switch actuated by the movement of a signal from danger to caution for supplying in one position of Said switch to the rails of the block in the rear current of a phase adapted to actuate one track relay only of said block and in another' position of said switch for supplying to the said rails current of a phase adapted to actuate both relays of said blocks.

ll. In a block signal system, signals for the blocks adapted to indicate danger, caution and clear, track circuits for the blocks, sources of alternating current for the track circuits, a pair of track relays for each block controlling the caution and clear indications according' as one or both relays are energized, each of said relays haring a winding supplied with current 'from the track circuit and a second cooperating winding supplied with alternating current independently of the track circuit, the currents supplied to said second windings didering in phase in the two relays of' each pair, and connections including a switch lactuated by the movement of a signal from danger to caution for supplying in one position of said switch to the rails of the block in the rear current of a phase adapted to actuate one track relay only oi said block and in another position of said switch for supplying to the said rails current or" a phase adapted to actuate both relays of said block and in an intermediate position of said switch for supplying' currents both simultaneously so as to supply ctv lill() to said rails aresultantcurrent of an intermediate phase.

l2. In a block signal system, signals for the blocks adapted to indicate danger, caution and clear, track circuits for the blocks, sources of alternating currentfor the track circuits. a pair of track relays for each block controlling the caution and clear indications according as one or both relays are energized, each of said relays having a winding supplied with current from the track circuit and a second cooperating winding supplied with alternating current independently of the track circuit, the currents supplied to said second windings differing in phase in the two relays of each pair by approximately ninety degrees, and means controlled by a train in one block for shifting the phase of the current supplied to the track circuit of 'he block in the rear of said means by approximately ninety degrees.

13. In a block signal system, signals for the blocks adapted to indicate danger, cautionf and clear, track circuitsfor the blocks, sources of alternating current for the track circuits, a pair of track relays for each block controllingl the caution and clear indications according as one or both relays are energized, each of said relays having a winding vsupplied with current from the track circuit and a second coperating winding supplied with alternating current independently of the track circuit, the currents supplied to said second windings differing in phase in the two relays of cach pair, the pairs of relays of adjacent blocks being reversely connected, and means controlled by the presence or absence of a train in one block for controlling the phase of the current supplied to the block in the rear of said means so as to actuate one only, or both, of the pair of relays for said block in the rear.

ll. In a block signal system, signals for the. blocks adapted to indicate danger, caution and clear, track circuits for the blocks, sources of alternating current for the track circuits` a pair of track relays for each block controlling the caution and clear indications according as one or both relays are energized, each of said relays having a winding supplied with current from the track circuit and a second cooperating winding supplied with alternating current independently of the track circuit. the currents supplied to said second windings differing in phase in the two relays of each pair, and means including a switch actuated by the movement of a signal from danger to caution for supplying' in one position of said switch to the rails of the block in the rear current of a phase adapted to actuate one track relay only of said block and in another position of said switch for supplying to the said rails current of a phase adapted to actuate both relays of said block, the sources and relays of adjacent blocks being reversely connected so that current from the source for one block produces a reverse torque in the adjacent relays upon the breaking down of the insulated joints between them.

l5. ln a block signal system, signals for the blocks adapted to indicate danger, caution, and clear, track circuits for the blocks, sources of alternating current for the track circuits, a pair of track relays for each block controlling the caution and clear indications according as one or both relays are energized, one of said relays being responsive to a current in the track rails of a phase to which the other does not respond, and connections including a switch actuated b y the movement of a signal from danger to caution arranged for supplying in different positions of said switch currents of diiferent phase to the tra-ck rails of the block in the rear, the sourcesand relays of adjacent blocks being reyersely connected so that current from. the source for one block produces a reverse torque in the adjacent relays upon the breaking down of the insulated joints between them.

1G. ln a block signal system, signals for the blocks adapted to indicate danger, caution, and clear, a polyphase transmission system for supplying current for the signal circuits, line transformers haring their primary windings connected to the several phases of the transmission system, a track transformer for each block having its secondary connected to the track rails, means controlled by the presence or absence of a train in a block for shifting the primary connections of the track transformer of the block in the rear of said means from one line transformer secondary to another to vary the phase of the current supplied to the track rails of the block in the rear, and a pair of track relays for each block controlling the caution and clear indications according as one or both relays are energized, one of said relays being' responsive to current in the track rails to which the other does not respond.

17. In a block signal system, signals for the lblocks adapted to indicate danger, caution, and clear, a polyphase transmission system for supplying' current for the signal circuits, line transformers haring their primary windings connected to the several phases of the transmission system, a track transformer for each block haring its secondary connected to the track rails, means controlled by the presence or absence of a train in a block for shifting the primary connections of the track transformer of the block in the rear of said means from one line transformer secondary to another to vary the phase of the current supplied to the track rails of the block in the rear, said means being arranged to establish one set of connections before breaking the other so as not to interrupt the flow of current to the track rails, impedances included in said connections to prevent short-circuiting the line transformer secondaries in changing from one set of connections to the other, and a pail of track relays for each block controlling the caution and clear indications according as one or both relays are energized, one of said relays being responsive to current in the track rails of a phase to which the other does not respond.

1S. ln a block signal system, signals for the blocks adapted to indicate danger, caution, and clear, a polyphase transmission system for supplying current for the signal circuits, line transformers having their primary windings connected to the several phases of the transmission system, a'tracl: transformer for each block having its secondary connected to the track rails, means controlled by the presence or absence of a train in a block for shifting the primary connections of the track transformer of the block in the rear of said means from one line transformer secondary to another to vary the phase of the current supplied to the track rails of the block in the rear, and a pair of track relays for each block controlling the caution and clear indications accordingl as one or both relays are energized, each of said relays having a winding supplied with current from the track rails and a second cooperating winding supplied with alteri'iating current independently of the track rails, the currents supplied to said second windings differing in phase in the two relays of each pair.

19. In a block signal system, blocks having a plurality of cut sections, a track circuit for each section, signals for the blocks adapted to indicate danger, caution, and clear, sources of alternating current for the track circuits, a pair of track relays for each track circuit or section, one relay of cach pair being responsive to current in the track circuit of al phase to which the other relay does not respond, means controlled by the presence or absence of a train in one block for shifting the phase of the current supplied to the adjacent track circuit or section of tho block in the rear of said means by approximately ninety degrees, and means controlled by the pair of relays for said track circuit or section for shifting the phase of the current supplied to the track circuit or section next in the rear by approximately ninety degrees.

20. ln. a block signal system, blocks having a plurality of cut sections, a track circuit for each section. signals for the blocks adapted to indicate danger, caution, and clear, sources of alternating current for the track circuits, a pair of track relays for each track circuit or section, one relay of each pair being responsive to current in the track circuit of a phase to which the other relay does not respond, means controlled by the presence or absence of a train in one block for shifting the phase of the current supplied to the adjacent track circuit or section of the block in the rear of said means without interrupting the flow of said current, and means controlled by the pair of relays for said track circuit or section for shifting the phase of the current supplied to the track circuit or section next in the rear without interrupt-ing the flow of said current.

21. ln a block signal system, blocks having a plurality of cut sections, a track circuit for each section, signals for the blocks adapted to indicate danger, caution, and clear, means for supplying alternating currents differing in phase for the track circuits, and a pair of track relays for cach track circuit or section, one relay of each pair being responsive to current in the track circuit of a phase to which the other relay does not respond, the two relays of the first track ircuit or section of a block controlling the caution and clear indications of the signal for such block according as one or both relays are energized, and the two relays of the track circuit or section next in advance controlling the phase of the current supplied to the first track circuit or section and arranged to shift said phase ap- Droximately ninety degrees.

29. In a block signal system, blocks having a plurality of cut sections, a track circuit for each section, signals for the blocks adapted to indicate danger, caution, and clear, means for supplying alternating currents differing in phase for the track circuits, and a pair of track relays for each track circuit or section, one relay of each pair being responsive to current in the track circuit of a phase to which the other relay does not respond, th-e two relays of the irst track circuit or section of a block controlling the caution and clear indications of the signal for such block according as one or both relays are energized, and the two relays of the track circuit or section next in advance controlling the phase of the current supplied to the rst track circuit or section and arranged to shift said phase without interrupting the current How,

Q3. In a block signal system, blocks having a plurality of cut sections, a. track circuit for each section, signals for the blocks adapted to indicate danger, caution, and clear, means for supplying alternating currents differing in phase for the track circuits, and a pair of track relays for each track circuit or section, one relay of each pair being responsive to current in the track circuit of a phase to which the other relay does not respond, the two relays of the first track circuit or section of a block .controlling the caution and clear indications of the signal for such block according as one or both relays are energized and the two relays of the track circuit or section next. in advance controlling the phase of the current supplied to the first track circuit or section, the contacts of the last-mentioned relays being so connected that when both relays are denergized the first track circuit is disconnected from the source of current, when one relay is energized current of one phase is supplied to said track circuit, and when both relays are energized curr-ent of another phase is supplied to said track circuit.

24. In a block signal system, blocks having a plurality of cut sections, a track circuit for each section, signals for the blocks adapted to indicate danger,l caution, and clear, means for supplying alternating currents differing in phase for the track circuits, and a pair of tra-ck relays for each track circuit. or section, one relay of each pair being responsive to current in the track circuit of a phase to which the other relay does not respond, the two relays of the first track circuit or section of a block controlling the caution and clear indicatio-ns of' the signal for such block according as one or both relays are energized and the two relays of the track circuit or section next in advance controlling the phase of the current supplied to the first track circuit or section, the contacts of the last-mentioned relays being so connected that when both relays are deenergized the first track circuit is disconnected from the source of current, when one relay is energized current of one phase is supplied to said track circuit, and when both relays are energized current of another phase is supplied to said track circuit, the change from one phase to the other being made without interrupting the current flow.

25. In a block signal system, blocks having a plurality of cut sections, a track circuit fo-r each section, signals for the blocks adapted to indicate danger, caution, and clear, means for Supplying alternating currents diliering in phase for the track circuits, a pair of track relays for each track circuit or section, each having a winding supplied with current from the track circuit and a second coperating winding supplied with alternating current independently of the track circuits, the currents supplied to said second windingsdifi'ering in phase in the two relays of each pair, the two relays of the lrst track circuit or section of a block controlling the caution and clear indications of the signal for such block according as one or both relays are energized and the two relays of the track circuit or section next in advance controlling the phase of t-he current supplied to the first track circuit or section.

26. In a block signal system, blocks having a plurality of cut sections, a track circuit for each section, signals for the blocks adapted to indicate danger, caution, and clear, means for supplying alternating currents differing in phase for t-he track circuits, a pair of track relays for each track circuit or sect-ion, each having a winding supplied with current from the track circuit and a second coperating winding supplied with alternating current independently of the track circuit, the currents supplied to said second windings differing in phase in the two relays of each pair, the two relays of the first track circuit or section of a block controlling the caution and clear indications of the signal for such block according as one or both relays are energized, means controlled by the presence or absence of a train in one block for controlling the phase of the current supplied to the adjacent track circuit or section of the block in the rear, and contacts controlled by the two relays of said last named track circuit or section for controlling the phase of the current supplied to the track circuit or section neXt in the rear.

27. In a railway signaling system, a track circuit, a source of alternating current, a pair of relays each having a winding connected with the track circuit and a coperating winding supplied with alternatin current independently of the track circuit, the currents supplied to the last named windings diifering in character, and means for supplying currents of diii'erent character from the source to the track circuit whereby one or both of the relays will be operated.

In witness whereof,` I have hereunto set my hand this 5th day of August, 1909.

LAURENCE A. HAWKINS.

Witnesses:

BENJAMIN B. HULL, EDWARD WILLIAMS.

Copies of this patent may be obtained for ve cents each, by addressing the Commissioner of Patents, Washington, D. C.

It is hereby certified that in Letters Patent No. 1,094,441, granted April 28, 1914 Snupon the application of Laurence A. Hawliiins, of Schenectady, New-York, for an L iniprovement in Block-Signal Systemseirors appear in the printed .Specification correction as follows: Page 5, linee 89, strike out the words for supplyvivng, and same page and line, after the word switch insert the wor-drs for supp@- yging; page 6, line 129, after the word supplying insert the Word batik/z; same page 4line 130, strike out the word bothg ancll'that the said Letters Patent should be read with these corrections therein that the'same may conform to they record of the case in the Patent Oliice. y l

Signed and sealed this 23rd day of June,{i-A. 1914.

' R. F. WHlTEHEAD,

Acting Uomfhssonelof Patents.

[SEAL] 

